When Prof. Condon and Ms. Dow measured each for economic and environmental efficiency, they produced some surprising comparisons.

For energy use and cost per passenger mile, the tram and LRT bested the rest. Put four people in a Prius, though, and it's only a bit worse than a loaded diesel bus.

Carbon output? The tram, trolley bus, SkyTrain and LRT all run on electricity, so their outputs were vastly lower than the diesel buses and autos, especially given B.C.'s hydro power.

But here's the zinger: Add up all costs for each form of transportation - capital, operating and energy - and guess which is most expensive per passenger mile? SkyTrain - even more than the gas-hogging SUV and nearly twice the winner, which is - you guessed it - the tram."